Oklahoma Tax Deadlines
State income tax filing deadlines, extensions, and estimates for 2026.
Oklahoma Tax Commission
https://oklahoma.gov/tax.html
individual deadline
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: State income tax return
Conforms to the federal calendar-year due date unless the state announces relief.
Estimated Payments
Sole Proprietorship deadline
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: State income tax return
Conforms to the federal calendar-year due date unless the state announces relief.
Estimated Payments
Partnership deadline
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: State business income tax return
Calendar-year due date follows federal timing for pass-through entities.
S Corporation deadline
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: State business income tax return
Calendar-year due date follows federal timing for pass-through entities.
C Corporation deadline
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: State corporate income tax return
Calendar-year due date follows federal timing for corporations.
Estimated Payments
LLC deadline
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: State business income tax return
Calendar-year due date follows federal timing for pass-through entities.
Nonprofit deadline
Due: May 15, 2026
Extension: Nov 15, 2026
Form: State nonprofit return
Nonprofit annual return generally due the 15th day of the 5th month.
Estimated Tax Payments
View all quarterly estimated payment due dates for Oklahoma.
FAQ
Does Oklahoma conform to federal due dates?
Many Oklahoma deadlines follow the federal calendar. Always confirm on Oklahoma Tax Commission.
Where can I file Oklahoma tax forms?
Visit Oklahoma Tax Commission at https://oklahoma.gov/tax.html for official forms and e-file options.